drm/i915/gtt: Reorder aliasing_ppgtt fini

drm/i915/gtt: Reorder aliasing_ppgtt fini

To allow ourselves to use a first class vma for the aliasing_ppgtt page
directory, we have to reorder the shutdown on module unload to remove
and unpin the aliasing_ppgtt before complaining about any objects left
in the GGTT.

Signed-off-by: Chris Wilson <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Mika Kuoppala <[email protected]>
Cc: Matthew Auld <[email protected]>
Reviewed-by: Matthew Auld <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]